docs: def _encode_filename_header(self, filename):
          """
          The filename, encoded to use in a ``Content-Disposition`` header.
          """
          # Based on https://www.djangosnippets.org/snippets/1710/
          user_agent = self.request.META.get('HTTP_USER_AGENT', None)
          if 'WebKit' in user_agent:
              # Support available for UTF-8 encoded strings.
              # This also matches Edgee.
              return u'filename={}'.format(filename).encode("utf-8")
          elif 'MSIE' in user_agent:
              # IE does not support RFC2231 for internationalized headers, but somehow
              # percent-decodes it so this can be used instead. Note that using the word
              # "attachment" anywhere in the filename overrides an inline content-disposition.
              url_encoded = quote(filename.encode("utf-8")).replace('attachment', "a%74tachment")
              return "filename={}".format(url_encoded).encode("utf-8")
          else:
              # For others like Firefox, we follow RFC2231 (encoding extension in HTTP headers).
              rfc2231_filename = quote(filename.encode("utf-8"))
              return "filename*=UTF-8''{}".format(rfc2231_filename).encode("utf-8")